Fundamental Studies of Beta Phase Decomposition Modes in Titanium Alloys.
Abstract
These studies on diffusional phase transformations in titanium and related alloy systems are intended to develop further the scientific base needed to design alloys based upon these transformations which may exhibit significantly improved combinations of mechanical properties. Kinetics of beta yields alpha sub m massive transformation were compared with those of grain boundary proeutectoid alpha precipitation in Ti-Ag and Ti-Co alloys, using measured or calculated nucleation and growth kinetics data and Cahn analysis of overall transformation kinetics of grain boundary nucleated reactions, successfully explained presence of massive transformation only in Ti-Ag and alpha allotriomorphs only in Ti-Co. New explanation developed, on thermodynamic grounds, for replacement of 'normal' proeutectoid alpha plates with a well-formed 'black plates' alpha + lower reaction temperatures. Bainite nodules in hypereutectoid Ti-Cr and in hypoeutectoid Ti-Co and Ti-Fe were found to exhibit misfit dislocation and ledge structures. Nodules in Ti-Cr grew at approximately volume diffusion-controlled rates; but reanalysis is now needed in terms of ledge mechanism. Eutectoid alpha is often found to differ slightly in orientation from adjacent proeutectoid aplha plates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 24, 1985
- Accession Number
- ADA154122
Entities
People
- A. M. Dalley
- E. S. K. Menon
- H. I. Aaronson
- H. J. Lee
Organizations
- Carnegie Mellon University